A logic circuit includes various logic gates, such as inverters, NAND gates and NOR gates. The logic circuit plays an important role in various application including data processing, logic operation, high speed communication, and central processing unit. In deep sub-micron integrated circuit technology, the logic circuit progressed to smaller feature sizes for higher packing density. However, the existing structure of a logic circuit still has various aspects to be improved for its performance and further enhanced packing density. It is therefore desired to have a new structure and design of a logic circuit to address the above concern with increased packing density.